Solar panel and multiple regulators

[dogsbreath]

Want to charge a number of batteries from a single solar panel. As batteries are different sizes - small motorbike to large marine I was thinking of using a large single panel and a number of cheap PWM regulators matched to suit each battery. Did not wish to parallel batteries up as some have low max charging rates.
Anybody done this previously?

[Tiny]

Hmm, interesting.

Definitely wouldn't parallel the batteries. Not without isolation switching.

Some regulators when connected to the same source can suffer from latching, that is; they are affected buy the other regulator/s & behave incorrectly.

Some regulators are designed for charging multiple batteries, most are not.

Best option for me would be to use 1 solar panel & 1 good quality regulator, then use VSR's (Voltage Sensitive Relays) to add more batteries.

I use on of these VSR's on my wifes vehicle to charge the caravan &/or run the caravan fridge.
I also have a similar VSR called a Redarc for my dual battery setup in my LandCruiser.
Both work exellently.


They are $70 each, however, what are your batteries worth & how much are the cheap PWM regs going to cost anyway??

You can read about them here

Just my opinion. See what others have to say.

[gordon_s1942]

Most NiCad chargers tell you not to mix AA/AAA/C and D type batteries together so would I be wrong in thinking that this would apply to Lead Acid batteries too of different sizes?

[hkp168]

I have been using one solar panel with two batteries. One of batteries is connected to a PWM regulator while the other is connected to a MPPT regulator.
The MPPT regulator can take 8-32VDC input so there should not be a problem even if the PWM regulator is in 'charge mode'. I was thinking of using the 'VSR' solution but decided to give it a go.

Hk

[dogsbreath]

System will be used more for a maintenance charge. The other risk with batteries in parallel is if one goes down it can take the rest with it. Not to mention the current/fire potential if a short was to occur.
Might give it a go and see what comes from it.
The main concern would be using a lower rated regulator than what the solar panel can provide. Are the regulators self limiting as far as their potential power input is concerned? ie Can you fit a 10 watt regulator up to a 200watt panel?

[Tiny]

Most Regulators will self regulate permanently when overloaded. Some will have an inbuilt fuse, some will just fry the circuit board &/or relays.

I fried a 20amp regulator by running 18 amp micro hydro 24/7. Still have the fried board as a reminder. It melted the main power rail on the board.
Had 20A fuse blow on another every month or so, until I pulled it apart upgraded some parts, wiring & installed 25A fuse. no more probs.

200W @ 12.6V = 15.87 Amps (theoretical max output, more likely will max a lot lower, 12 or 13 amp.)

Way over the rated 10 amp reg, will fry it for sure the first time it gets a strong burst of sun.

I would use a 15 amp minimum, however to be safe I would use 20 Amp reg, 20A rated wiring & fuses.

There is a reason why 10A regs cost less than higher capacity regs. Component load rating.

"The other risk with batteries in parallel is if one goes down it can take the rest with it. Not to mention the current/fire potential if a short was to occur."

Not if you use suitable protection, like VSR's or isolating switches or diodes. Don't forget to use fuses to each battery.


Edit: BTW, don't forget to keep an eye on the electrolyte levels of your flooded cell Lead Acid batteries, especially if the regulator/s you choose are not programmable. Long periods of higher than optimum float voltage can off gas a lot of hydrogen, make sure adequate ventilation to prevent gas build up.
The cheaper not programmable regs may float & or boost charge your batteries at higher or lower voltage levels than optimum, so keep an eye on the voltage as well. Float, Boost & Absorption (if available)

[hkp168]

I didn't mean putting batteries in parallel. I know that it will be difficult/impossible if batteries are in different capacities or age. One of my setup is having one solar panel connected to two regulators (each connects to an individual battery). In theory, the batteries are not operated in parallel and they are isolated by regulators. Good regulators usually have overcurrent/voltage/polarity protection and fuses. Trying using multi-stage chargers (with temperature compensation). They can prevent your batteries from over-charging.

Nowadays solar panels are much cheaper than they used to be, it will be easier to stick with one panel/one battery approach. I don't thing there will be probelm using a 10W regulator with a 200W panel provided that the max input voltage range of the PWM regulator is more than the panel's output voltage. The down side is you are not using the full potential of the panel on a sunny day.

It will be a good idea to use larger wires minimising voltage drops (and heat) for heavy loads (eg. a water pump). You can also add a power distribution panel with fuses or circuit breakers for further protection.

[Tiny]

Nowadays solar panels are much cheaper than they used to be, it will be easier to stick with one panel/one battery approach. I don't thing there will be probelm using a 10W regulator with a 200W panel provided that the max input voltage range of the PWM regulator is more than the panel's output voltage. The down side is you are not using the full potential of the panel on a sunny day.

WTF: I guess you meant 10A regulator & you are referring to a 24 volt regulator to make 240W load rating?
OP has stated that the cells are of varying size (assume A/Hour capacity & physical size), not voltage.
The Motorcycle battery is definitely going to be 12v. The batteries therefore can't be connected in series to make 24 volt, nor can they be charged using a 24 volt reg individually; except possibly the large marine battery that could be 24v, however most marine systems for smaller vessels are 12v????
I do know the outback range of regs & probably some others, can input a 24 volt panel & output to 12 volt, they are not cheap & so I assume, maybe incorrectly, that the OP is talking about a 12 volt panel not 24 Volt.
Some large capacity solar panels can be configured inside the junction box to output for a 12 or 24 volt system. Not both at the same time though that I know of.

Since the OP has not corrected me when answering using 12 Volt, I will assume again that we are talking about a 12 volt system.

Perhaps the OP could specify his system voltage to clarify this for us to clear the assumption.

[dogsbreath]

Yes definitaley all 12v automotive and marine type batteries. Also looking at the 12v panels which usually have a output of up to 21v. Main concern is wether the 10w regulator for instance is self limiting or will fry itself with a greater input current available to it with a larger panel. I can appropriately fuse each regulator to its capacity as on the input side as a precaution as well.

[Tiny]

OK then I stand by what I said in post 6;

Most Regulators will self regulate permanently when overloaded. Some will have an inbuilt fuse, some will just fry the circuit board &/or relays.

200W @ 12.6V = 15.87 Amps (theoretical max output, more likely will max a lot lower, 12 or 13 amp.)

Way over the rated 10 amp reg, will fry it for sure the first time it gets a strong burst of sun.

I would use a 15 amp minimum, however to be safe I would use 20 Amp reg, 20A rated wiring & fuses.

There is a reason why 10A regs cost less than higher capacity regs. Component load rating.

BTW, don't forget to keep an eye on the electrolyte levels of your flooded cell Lead Acid batteries, especially if the regulator/s you choose are not programmable. Long periods of higher than optimum float voltage can off gas a lot of hydrogen, make sure adequate ventilation to prevent gas build up.
The cheaper not programmable regs may float & or boost charge your batteries at higher or lower voltage levels than optimum, so keep an eye on the voltage as well. Float, Boost & Absorption (if available)